Abstract
Unconventional shale drilling has developed rapidly during the last decade. The development of substantial prospectsespecially in shale gas playsrequires advanced technologies and prudent well monitoring. Many new operational challenges are associated because of simultaneous operationssuch as drilling and fracturing nearby wells.
While drillingthe interaction of the fractures from nearby wells results in pressure communication and unexpected well kicks. Because of the low porosity of those tight reservoirsthose uncommon well kicks have so far not been severebut taking the time to control wellbore pressures adversely affects the efficiency of the drilling process and increases the nonproductive time. Additionallyas fracturing becomes more efficientand conductivity increasespossible future events might have much more dramatic consequences. This paper presents a method that uses the positional uncertainty of the well being drilledpositional uncertainty of the fractured/fracturing wellsand uncertainty of the fracture length and fracture orientation to avoid this problem. The paper discusses the reasons and challengestechniquesand lessons learned to solve the simultaneous moving boundary conditions between the reference wells and multiple offset wells. The method of explicit solution avoids a trial-and-error procedure and provides excellent maneuverability of planning requirements. The modified model and methods provided the use of exact mathematical solutions and uncertainty ellipses estimates.
This method can also be used to monitor the influence of other variablessuch as temperature cyclingoil drainage distancewellbore storage effectand reservoir pressure transients. The method presented can be used in the planning stage to ensure optimal well placement; it can also be used for designing super fractures between wells. The study indicates that the use of real-time data from drilling and fracturing wells can predict the need for remedial action.
